This project concerns both experimental and theoretical research on the mechanism of pathological vocal-cord vibrations as well as new progress in the diagnosis and medical treatment of voice disorders. The investigations are based primarily on the theoretical model of the normal vocal cords developed by Ishizaka and on the preliminary experiments on asymmetric vibrations of extirpated larynges by Isshiki. The specific aims of the project are: (1) the experimental investigation of the classification of vibratory patterns of pathological vocal cords, (2) the theoretical modeling of pathological vocalcord vibration and voice production, and (3) the acoustic detection of laryngeal pathology. The experimentation is being done primarily through high-speed motion pictures of vocal fold vibration in extirpated larynges in which pathologic conditions are simulated by artificially and systematically altering the mechanical characteristics of the folds. Mechanical measurements are also made on the same specimens. The theoretical aspect of the project involves digital simulation of the mechanically altered folds using an asymmetric 4-mass model of the vocal folds.